What is “matter” anyway?
The teaching of chemistry and matter is one area in which I often find myself falling victim to the curse of knowledge. I know what matter is. I know what an element is. I know what atoms are. I cannot imaging what it would be like to not understand these concepts.
I use these words – “matter,” “elements,” “atoms” – and my students complacently nod their heads and participate but, if I ask the students what the words actually mean, they can usually only spout off to me some verbatim definition that they learned in another class and the students do not truly understand what these things are.
The (recently renamed) National Science Teaching Association has a great set of assessment probes for “Uncovering Student Understanding” that can be very helpful for doing exactly that – figuring out what students really think, what misconceptions they have, and what knowledge gaps need to be filled.
In this lesson I use a modified version of the assessment probe “What is Matter?” to help my students explore their understanding of some basic chemistry vocabulary.
We start by giving the student groups a set of cards depicting various items
Have the students put all the cards out on their table and sort into two groups “matter” or “not matter.” Be sure students can explain their justification for the placement in each grouping.
Though this activity may seem straightforward, I’ve found it often brings up some very interesting discussion, especially regarding light, electricity, and air. The discussions were engaging and interactive enough that I actually selected this particular lesson to use for one of my video submissions for National Board Certification in Early Adolescent Science.
Some ways to address potential misconceptions:
- Air is not matter – get a balloon. Blow up the balloon. Students agree you blew air into the balloon. If air is not matter, what makes the balloon get bigger?
- Light is matter – take a lightbulb. Close the doors. Turn on the light. Does the room get full of light? If we kept the light on, would the light eventually fill up the whole room and squash us?
- Smoke is not matter – light a candle. Hold a petri dish (carefully) over the candle. Soot collects on the petri dish. Is soot matter? If so, smoke is matter. You can also use the example of students being told to crawl on the floor during a fire. Smoke rises and would fill your lungs because “something” is there.
Eventually, students collaborate to develop a working definition of “matter” that is more student-friendly than what the standard dictionary provides:
We usually decide that matter is “stuff” that “takes up space” and leave it at that.
This can be a good point to pre-teach or review some key vocabulary for the matter and chemistry units. I like to use a mind map that we fill in either all at the beginning and the revisit throughout the unit or add to as we go along.
You can also add extensions to the side of the mind map to include the properties of elements vocabulary! Mind maps are fun. Try having students create their own with Mindomo, too, if you have technology. I appreciate that Mindomo has single sign on integrated with Google so my kiddos (who have school issued Gmail addresses) don’t have to remember another password.
That’s it for matter. I always end the lesson reminding my students that, no matter what matter is, they always matter to me!